Typically, to mount trays, for example, arm rests, table extensions, keyboard holders, etc., onto platforms, such as table tops, clamps are used. A clamp is generally fixedly attached to a tray at one end and can be mounted onto a platform at another end to hold the tray in position against the platform while in use. The clamp may be designed for use with platforms having a particular thickness or may include a spring-clip arrangement for adapting the clamp to small variations in platform thicknesses. Such clamp-tray arrangements are generally used for mounting the tray for a particular purpose and may be temporarily mounted onto the platform such that the tray can be removed after use. However, typical clamp-tray arrangements tend to be bulky and take time and effort to mount and dismount.